Vacuum intensifier

ABSTRACT

A vacuum intensifier for maintaining an operational partial vacuum within a predetermined range to effectively operate a vacuum powered device. A housing is divided into a power section and an evacuation section. The power section contains a first diaphragm which separates the power section into first and second chambers. The evacuation section contains a second diaphragm having a smaller area than the first diaphragm which separates the evacuation section into third and fourth chambers. The first and second diaphragms are connected together to correspondingly move in response to alternating porting of partial vacuum from a source and atmospheric pressure to the first and second chambers. Upon movement of the second diaphragm the third and fourth chamber will alternately inhale air from the vacuum powered device and exhale air to be dumped into a conduit going to the source of partial vacuum to uniformly lower the pressure level in the vacuum powered device.

tlnited States Patent [191 Sobieralski [73] Assignee: The Bendix Corporation, South Bend, Ind.

[22] Filed: Sept. 20, 1971 [21] Appl. No.: 181,991

[75] Inventor:

[ June 26, 1973 Primary Examiner-William L. Freeh Assistant ExaminerGregory LaPointe Attorney-Leo H. McCormick, Jr. et a1.

[57] ABSTRACT A vacuum intensifier for maintaining an operational partial vacuum within a predetermined range to effectively operate a vacuum powered device. A housing is divided into a power section and an evacuation section. The power section contains a first diaphragm which separates the power section into first and second chambers. The evacuation section contains a second diaphragm having a smaller area than the first diaphragm which separates the evacuation section into third and fourth chambers. The first and second diaphragms are connected together to correspondingly move in response to alternating porting of partial vacuum from a source and atmospheric pressure to the first and second chambers. Upon movement of the second diaphragm the third and fourth chamber will alternately inhale air from the vacuum powered device and exhale air to be dumped into a conduit going to the source of partial vacuum to uniformly lower the pressure level in the vacuum powered device.

13 Claims, 2 Drawing Figures [52] US. Cl 417/14, 417/344, 417/395,

. 417/404 [51] Int. Cl. F04!) 49/00 [58] Field of Search 417/393, 395, 345, 417/264, 403, 404, 14, 344; 91/344, 346

[56] References Cited UNITED'STATES PATENTS 943,848 12/1909 Simonds 417/395 3,044,405 7/1962 Bent 91/346 2,973,717 3/1961 Mendig 417/345 2,699,120 I 1/1955 Schweisthal 417/403 3,151,804 10/1964 La Flame 417/264 3,652,187 3/1972 Loeffler et a1. 419/193 PATENTEU M26 1975 SHEEI 1 BF 2 ATTORNEY PATENTEUJUH 2 6 I973 SlEETZBFZ FIG. 2

INVENTOR. LEO J. SOBIERALSKI BY I ATTORNEY VACUUM INTENSIFIER BACKGROUND OF THE INVENTION Atmospheric pressure is the actuating force used to create a pressure differential across a normally vacuum suspended diaphragm to operate a vacuum power brake system of a vehicle powered by an internal combustion engine. A partial vacuum is created at the intake manifold due to the pumping action of thepistons in the engine as they draw air into the cylinders. The resulting partial vacuum occurs because the throttle valve partly obstructs the flow of incoming air through the carburetor so that air cannot enter the manifold fast enough to keep with the rapidly descending pistons. Consequently, a certain amount of air must fill a space much larger than it would occupy under atospheric conditions, producing reduced air pressure or a partial vacuum which is used to suspend the diaphragm of the servomotor. The output force produced by the vacuum power brake is directly dependent upon the difference in the atmospheric pressure and the partial vacuum produced. However, in some presently designed engines equipped with emission control systems, the exhaust gases are recirculated through and dumped in the manifold. This amount of dumped exhaust gas will reduce the pressure differential between the atmosphere and the partial vacuum produced. Thus, in operating such a power brake system, the servomotor is incapable of producing the necessary operating force to pressurize a master cylinder supplying fluid to each wheel cylinder to bring a vehicle to a stop within a required'distance.

In copending U. S; application, Ser. No. 143,419, filed May 14, 1971 and incorporated by reference, an intensifier having the ability for sensing the available partial vacuum supplied a vacuum power braking system and generating an additional source of vacuum was developed. In the primary embodiment, a venturi flow device was used to obtain the additional reduction in the air pressure level while in a secondary embodiment, a single power stroke device was used to pull air from the vacuum powered system. As in-all venturi systems, a constant flow of air is required to create the desired pressure drop which could affect the operation of the vehicle since this air flow is dumped into the exhaust manifold. While in the secondary'embodiment the need for constant air flow is eliminated, however, the time for reducing the pressure level is directly proportional to the size of the single diaphragm used in the single stroke evacuation operation.

SUMMARY OF THE INVENTION To maintain an effective operating partial vacuum in a vacuum power braking system,'I have devised a multiphase vacuum intensifier apparatus. In the intensifying apparatus, sensing means compares the partial vacuum supplied to the vacuum powered braking system for controlling the flow of partial vacuum to a power chamber. The power chamber is divided into a first chamber and a second chamber. Actuator means alternately ports partial vacuum and air at atmospheric pressure to the first and second chambers to cause the first wall means to reciprocate and supply a force to shaft means connected to a second wall means. The second wall means divides an evacuation chamber into third and fourth chambers. Flow control means alternately permit the second wall means to inhale air from the vacuum powered system and to exhale air to be dumped into the source of partial vacuum from the third and fourth chambers. Through my intensifier device the partial vacuum pressure is uniformly reduced to a predetermined operational level.

It is an object of this invention to provide a vacuum power braking system with a multi-phase intensifier to maintain the vacuum level in the system within a predetermined range.

It is another object of this invention to provide an intensifying means with a sensor means for supplying an operational partial vacuum on demand.

It is a still further object of this invention to provide an intensifier means for reducing the initial pressure level of a partial vacuum to a predetermined pressure which is a direct function of the area of wall means in a power chamber when compared to the area of wall means in an evacuation chamber.

These and other objects will become apparent to those who read this specification and view the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of a vacuum power braking system with a sectional view of an intensifier constructed in accordance with the principles of my invention for maintaining the partial vacuum level in the system within a predetermined range.

FIG. 2 is a sectional view taken alongline 2-2 of FIG. lto show the relationship between the actuation lever arm and the output shaft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the power braking system 10 shown in FIG. 1, a servomotor l2 operated by partial vacuum supplied by conduit 14 connected to the intake manifold 16 of a vehicle supplies the operational fluid pressure for energizing the front brakes l8 and the rear brakes 20 of the vehicle. Sensor means 24 connected to conduit 14 compares the pressure level of the partial vacuum supplied to the servomotor with air at atmospheric pressure to control the communication between the intake manifold 16 and an intensifier means 22. The intensifier means 22 in response to the sensor means 24 will generate additional partial vacuum upon demand to maintain the operational level of the partial vacuum in the servomotor 12 within a predetermined range.

In more particular detail the intensifier means 22 consists of a housing 26 having a power chamber 28 and an evacuation chamber 30 separated by an atmospheric chamber 32. Air at atmospheric pressure freely enters the atmospheric chamber 32 through filter 33. A partition wall 34 separates the atmospheric chamber 32 from the power chamber 28.

The power chamber 28 is divided by a first wall means 36 into a first chamber 38 and a second chamber 40. The first wall means 36 consists of a diaphragm 42 with an outer periphery 44 retained by the housing 26 and an inner periphery 46 held between a first backing plate 48 and a second backing plate 50 held together by keeper nuts 52 and 54 on shaft means 56.

The partition wall 34 has a first passageway 58 which connects a first bore 60 and a third bore 64 with a conduit 66 connected to the manifold 16 where a partial vacuum can be produced. The first bore 60 has an annular seat 68 surrounding a second passageway 70 going to a second bore 62.

Shaft means 56 is retained in the second bore 62 by bearing seals 72 and 74. Shaft means 56 has a tubular passage 76 to permit communication between the second passageway and the first chamber 38.

The third bore 64 extends clear through the partition wall 34 to permit communication between the atmospheric chamber 32 and the second chamber 40.

First valve means 78 located in the first bore 60 has a flexible tubular poppet member 80 with one end 84 held against the rear of the first bore 60 by an annular retainer ring 82. The other end 86 of the poppet member 80 has an inwardly projecting annular lip 88 which is snapped over a support disc 90. A centrally held stem 94 has a cap 92 on one end and a cross pin 96 on the other end. A conical spring 98 has its base retained on the support disc and its apex held against an annular member 100 adjacent the cross pin 96.

Second valve means 102 located in the third bore 64 has a flexible tubular poppet member 104 with one end 106 held against the rear of the third bore 64 by an annular retaining ring 108. The other end 110 of the poppet member 104 has an inwardly projecting annular lip 112 which is snapped over a support disc 114. A centrally held stem 116 has a cap 118 on one end and a cross pin 120 on the other end. A conical spring 122 has its base retained on the support disc 114 and its apex held against an annular member 124 adjacent the cross pin 120.

A lever arm 126 has one end 128 pivotally attached to cross pin 96 and the other end 130 attached to cross pin 120. The lever arm 126 is pivotally retained at its midpoint by pivot pins 131 and 132,'as shown in FIG. 2. A pair of springs 134 and 136 attached to the cross pin 96 extends to a cross pin 138 on the shaft means 56.

The shaft means 56 extends through the atmospheric chamber 32 past seal 140 and into the evacuation chamber 30. The end of the shaft means 56 in the evacuation chamber is attached to a second wall means 142 by bolt 145. The second wall means 142 divides the evacuation chamber 30 into a third chamber 144 and a fourth chamber 146. The wall means 142 consists of a diaphragm 148 having an outer periphery 150 secured to the housing 26 and an inner periphery 152 retained between backing plates 154 and 156 held against shoulder 158 by bolt 145. i

A first passage 160 connects the third chamber 144 with a fourth bore 162 located in a side projection 169 on the housing 26. A second passage 164 connects the fourth chamber 146 with a fifth bore 166 also located in the side projection 168. The housing 26 forms a first annular seat 168, adjacent the bottom of the fourth bore 162 and a second annular seat 170 adjacent the bottom of the fifth bore 166. A cross bore 172 connects the fourth 162 and fifth 166 bores to a third passageway 174 which tees into the first passageway 58. A fourth passageway 176 located in the side projection 168 directly connects the fourth bore 162 with the fifth bore 166 and conduit 178 which joins conduit 14 supplying the servomotor 12 with partial vacuum.

A first control means 180 located in the fourth bore 162 regulates the flow of air into and out of the third chamber 144. The first control means 180 consists of a flexible tubular poppet member 182 having one end 185 fixed against shoulder 186 by retaining ring 188 and an annular lip 190 and the other end snapped over a support disc 192. The support disc 192 has a tubular portion 194 with a plurality of openings 196. The tubular portion 194 surrounds stem 198 which has a cap 200 attached to one end and a retainer 202 attached to the other end. A first spring 204 positioned between the retaining ring 188 and the support disc 192 urges the flexible tubular poppet member 182 toward the annular seat 168 to close the communication between the first passage 160 from the third chamber and the third passageway 174. A second spring 206 positioned between the support disc 192 and the retainer 202 urges the cap 200 against the annular lip 190 to close communication between the first passage from the third chamber 144 and the fourth passageway 176 connected to the source of partial vacuum.

A second control means 208 located in the fifth bore 166 regulates the flow of air into and out of the fourth chamber 146. The second control means 208 consists of a flexible poppet member 210 having one end 212 fixed against shoulder 214 by retaining ring 216 and an inwardly projecting annular lip 218 on the other end. The annular lip 218 is snapped over a support disc 220. The support disc 220 has an annular tubular portion 222 with a plurality of openings 224. The tubular portion 224 surrounds stem 226 which has a cap 228 on one end and a retainer 230 on the other end. A first spring 232 positioned between the retaining ring 216 and the support disc 220 urges the flexible tubular poppet member 210 toward the annular seat 180 to close the communication between the second passage 164 from the fourth chamber 146 and the cross bore 172 going to the third passageway 174. A second spring 234 positioned between the support disc 220 and the retainer 230 urges the cap 228 against the annular lip 218 to close communication between the second passage 164 from the fourth chamber 146 and the fourth passageway 176 connected to the source of partial vacuum and the servomotor 12.

A check valve 240 having a cap 242 resiliently held against seat 244 by spring 246 is screwed into housing adjacent the end of the fourth bore 162. Check valve 240 will only permit the flow of air from the servomotor 12 toward the source of partial vacuum.

Conduit 178 connected to the partial vacuum supply conduit 14 going to the servomotor supplies the sensing means 24 with the same partial vacuum through inlet port 248 of housing 250. The sensing means 24 has an internal cavity divided into a partial vacuum chamber 252 and an atmospheric chamber 254. A diaphragm 256 seals the vacuum chamber 252 from the air supplied to atmospheric chamber 254 through port 258. The diaphragm 256 is sandwiched between a pair of backing plates 260 and 262. A spring 264 located in the partial vacuum chamber urges the diaphragm 256 toward the atmospheric chamber 254. A push rod 266, attached to the diaphragm backing plates 260 and 262 extends, through the housing 250 and is pivotally connected to a lever arm 268. Lever arm 268 operates a butterfly valve 220 to open and close the partial vacuum communication going to the power supply 28 of the intensifier.

MODE OF OPERATION OF THE PREFERRED EMBODIMENT When an operator pushes on pedal 209, the servomotor 12 is energized to supply pressurized fluid to operate the front 18 and rear 20 brakes to bring a vehicle to a stop. The energization of the servomotor 12 is accomplished by a pressure differential between a partial vacuum (from the manifold) and air at atmospheric pressure being created in the servomotor 12 to provide an actuating force to move a piston (not shown) in the master cylinder 211. When the piston in the master cylinder moves, hydraulic fluid under pressure is supplied to operate the braking system. The intensity of the out put force from the servomotor 12to the master cylinder 211 is directly dependent upon the created pressure differential. It is therefore necessary to maintain this within predetermined limits by controlling the created partial vacuum, since air at atmospheric pressure is relatively constant, to be able to predict the stopping distance for a vehicle from a given speed.

After each brake application the air at atmospheric pressure used to create the pressure differential is dumped into partial vacuum supply. Normally, the pressure level in the servomotor is reduced to that of the partial vacuum being produced at the intake manifold. The air in the servomotor is evacuated by flowing through conduit 14, conduit 177 into the fifth bore 166, out passageway 176, into the fourth bore 162, past check valve 2411, through conduit 210 and into the intake manifold 16. Simultaneously, the sensor means 24 receives the same partial vacuum level in chamber 252 that is present in the servomotor 12 through conduit 178. When the pressure level in the partial vacuum chamber 252 approaches atmospheric pressure, a near balanced pressure will be present across diaphragm 256. With a near balance across the diaphragm 256, spring 264 will move push rod 266, to the right as viewed in FIG. 1, causing lever arm 268 to open the butterfly valve 270. With butterfly valve 270 opened, a partial vacuum is communicated through the first passageway 58.

In the position shown, in FIG. 1, with the first valve means 78 held by the lever arm 126 away from the annular seat 68 partial vacuum enters the first bore 60 and goes through the second passageway 70 into the second bore 62. From the second bore 62, the partial vacuum is communicated through the tubular portion 76 of the shaft means 56 into the first chamber 38. The lever arm 126 acts against resilient means 122 to lift the cap 116 away from the annular lip 112 to permit air-at atmospheric pressure to enter into the second chamber 411. With partial vacuum in the first chamber 38 and air at atmospheric in chamber 40, a pressure differential will be created across wall means 36. This pressure differential will act on the area of the wall means to develop a force causing the shaft means 56 to move, to the left, as shown in FIG. 1, on bearing seals 72 and 74. When the first wall means 36 moves, the shaft means 56 will corespondingly move the second wall means 142. In this mode of operation, as the second wall means 142 moves, the air in the third chamber 144 will be forced or exhaled through the first passage 160 and acts on cap 200. Sufficient force on cap 200 will raise the flexible tubular member 182 by compressing spring 204 to unseat the annular lip 190 of the flexible tubular member 182 from the annular seat 168. With the annular lip 190 away from the annular seat l68,'the air in the third chamber will pass through the third passageway 174 and be dumped into the first passageway 58 to be evacuated away by the partial vacuum produced by the intake manifold.

Simultaneously, to the exhalation of air from the third chamber 144 as the second wall means 142 moves, a suction force will overcome spring 234 and pull the cap 228 away from the annular lip 218 to permit air to be inhaled or drawn from the servomotor 12.

When the first wall means approaches the bottom of its stroke the cross pin 138 on shaft means 56 will have moved past the cross pin 96 in such a manner that resilient means 134 will pull the first valve means toward the annular seat 68. When resilient means 134 positions the annular lip 86 on seat 68, cap 92 will be moved away from the annular lip 86 to permit air at atmospheric pressure to enter into the first bore 60. From the first bore 60, this air will be communicated to the first chamber 38. At the same time the lever arm 126 will move the annular lip away from seat 214 to permit the partial vacuum to be communicated through the third bore 64 into the second chamber 40, to reverse the pressure differential across the wall means 36. With the pressure differential reversed, the wall means 36 will move shaft means 56 in an opposite direction.

With the direction of movement of the second wall means 142 reversed, air is now exhaled from the fourth chamber 146 by forcing the cap 228 against the annular lip 218 causing the spring 232 to collapse. With spring 232 collapsed, the annular lip 218 is raised from seat permitting the air to flow into cross bore 172 around flexible tubular member 182 and into the third passageway 174. Any air in the third passageway 174 will be evacuated through the first passage by the partial vacuum produced at the intake manifold. Correspondingly air from the servomotor is inhaled into the third chamber 144, through a suction force overcoming spring 206 to allow cap 200 to move away from the annular lip 190.

The above reciprocating cycle is repeated until the partial vacuum pressure in the servomotor is reduced sufficiently as compared by sensor means 24 to permit air at atmospheric pressure to overcome spring 264 and move the diaphragm 256 to the left as viewed in FIG. 1. As the push rod 266 is moved, the lever arm 268 will close the butterfly valve 270 to stop communication between the partial vacuum produced at the manifold and the power section 28 of the intensifier.

The spring 264 in the sensor means 24 can be chosen so that upon a single application of the brakes by operation of the servomotor 12, the butterfly valve 276 will remain closed.

Initially the air evacuated from the system is dumped into the manifold 16 by flowing through conduits 14 and 176 and past check valve 240. Only then, if the partial vacuum in the servomotor drops below a predetermined value will the intensifier be activated to maintain a desired partial vacuum pressure level as a function of the areas of the first and second wall means 36 and 142.

I claim:

1. An intensifier for maintaining an operational partial vacuum level of a vacuum powered device within a predetermined range, said intensifier comprising:

' a housing having a power chamber and an evacuation chamber;

first wall means dividing the power chamber into a first chamber and a second chamber;

second wall means dividing the evacuation chamber into a third chamber and a fourth chamber;

said second wall means having a smaller area than the first wall means;

shaft means for rigidly connecting said first wall means to said second wall means;

a source of partial vacuum connected to said vacuum powered device; actuating means responsive to movement of said shaft means for alternately porting air at atmospheric pressure and partial vacuum from said source to the first and second chambers of the power chamber to create an operational pressure differential across said first wall means causing said shaft means to reciprocate and correspond-ingly move said second wall means; sensing means connected to the vacuum powered device for comparing the pressure level of the partial vacuum in the vacuum powered device with a control pressure, said sensing means controlling the communication of said partial vacuum to the power chamber for creating the operational pressure differential; first control means connected to the third chamber of the evacuation chamber, the source of partial vacuum, and the vacuum powered device; and

second control means connected to the fourth chamber of the evacuation chamber, the source of partial vacuum, and the vacuum powered device, said first and second control means operating in response to movement of said second wall means to alternately inhale and exhale air in the third and fourth chambers from the vacuum powered device to uniformly reduce the pressure level in said vacuum powered device below the available partial vacuum from said source, said reduced level in said vacuum powered device being a function of the areas of said first and second wall means.

2. The intensifier, as recited in claim 1, wherein said housing includes:

a partition wall separating said power chamber from an atmospheric chamber, said partition wall having a first bore, a second bore and a third bore, said partition wall having a first passageway connecting the first and third bores with the source of partial vacuum communicating through said sensing means;

said partition wall having a second passageway connecting said first and second bores, said first bore being opened to said atmospheric chamber, said second and third bores being opened to the second chamber and the atmospheric chamber, said shaft being sealed in said second bore and having an internal passage for connecting said second bore with said first chamber;

first valve means located in said first bore and connected to said shaft means for alternately porting partial vacuum from said first passageway and air at atmospheric pressure from said atmospheric chamber to said second passageway for transmission to said first chamber; and

second valve means located in said third bore and connected to said shaft means for alternately porting partial vacuum from said passageway and air at atmospheric pressure from said atmospheric chamber to said second chamber in an opposing sequence to said first valve means to create the operational pressure across the first wall means.

3. The intensifier, as recited in claim 2, wherein said sensing means permits communication of partial vacuum to said first passageway when the sensed pressure level is above a predetermined value and preventscommunication of said partial vacuum to the first passageway when the pressure level equals a predetermined value.

4. The intensifier, as recited in claim 3, wherein said housing further includes:

a projection adjacent said evacuation chamber having a fourth bore and a fifth bore, said housing forming a first annular seat at the bottom of the fourth bore around a first passage to the third chamber, said housing forming a second annular seat at the bottom of the fifth bore around a second passage to the fourth chamber, said housing having a third passageway connecting the fourth and fifth bores with the first passageway, said fourth bore being connected to said source of partial vacuum, said fifth bore being connected to said vacuum powered device and a fourth passageway connecting the fourth bore with the fifth bore to permit the vacuum powered device to be evacuated by the partial vacuum available from said source.

5. The intensifier, as recited in claim 4,wherein said first control means includes:

first flexible tubular means having one end secured to the interior of said fourth bore and an inwardly projecting annular lip on the other end;

first resilient means for urging said annular lip of the first flexible tubular means against the first annular seat to close the communication between the first passage going to the third chamber and the third passageway; and

first cap means resiliently held against said annular lip of the first flexible tubular means for closing communication between the third chamber and the fourth bore.

6. The intensifier, as recited in claim 5, wherein said second control means includes:

second flexible tubular means having one end secured to the interior of said fifth bore and inwardly projecting annular lip on the other end;

second resilient means for urging said annular lip of the second flexible tubular means against the second annular seat to close the communication between the second passage going to the fourth chamber and the third passageway; and

second cap means resiliently held against said annular lip of the second flexible tubular means for closing communication between the fourth chamber and the fifth bore.

7. The intensifier, as recited in claim 6, wherein said first valve means includes:

third flexible tubular means having one end secured to the interior of said first bore and an inwardly projecting annular lip on the other end;

first stem means located inside said third flexible tubular means;

disc means secured to one end of said first stem means; and

first spring means located between the annular lip of the third flexible tubular member and a retainer member on the first stem means for urging said first disc means against said annular lip of the third flexible means for closing communication between the first bore and the atmospheric chamber.

8. The intensifier as recited in claim 7, wherein said second valve means includes:

fourth flexible tubular means having one end secured to the interior of the second bore and an inwardly projecting annular lip on the other end;

second stem means located inside said fourth flexible tubular means;

second disc means secured to one end of said second stem means; and

second spring means located between the annular lip of the fourth flexible tubular means and a retainer on the second stem means for urging said second disc means against said annular lip of the fourth flexible means for closing communication between the third bore and theatmospheric chamber.

9. The intensifier as recited in claim 8, wherein said intensifier further includes:

flow control means located between the connection of the fourth bore and the source of partial vacuum to only permit flow of air from the vacuum powered device toward the source of partial vacuum.

10. The intensifienas recited in claim 9, wherein said actuator means further includes:

a lever arm pivotally attached to the housing at its midpoint having one end attached to the other end of said first stem means and the other end of said second stem means; and

third resilient means secured to said shaft means and said lever arm for alternately holding said first and second disc means against the annular lip of the third and fourth flexible tubular means to permit the partial vacuum and air at atmospheric pressure access to the first and second chambers.

11. The intensifier, as recited in claim 10, wherein movement of said second wall means in a first mode causes inhalation of air into the third chamber from said fourth passageway connected to the vacuum powered device by unseating said first cap means and exhalation of air from the fourth chamber by overcoming the second resilient means to compress the second flexible tubular means to allow air to pass around the second annular seat and be dumped into the third passageway.

12. The intensifier, as recited in claim 11, wherein movement of said second wall means in a second mode causes inhalation of air into the fourth chamber from the fifth bore connected to the vacuum powered device by unseating said second cap means and exhalation of air from the third chamber by overcoming the first resilient means to compress the first flexible tubular means to allow air to pass around the second annular seat and be dumped into the third passageway.

13. The intensifier, as recited in claim 12, wherein said sensing means includes:

a housing having an interior cavity with an atmospheric port and an operational partial vacuum port connected to the vacuum powered device;

diaphragm means for dividing the internal cavity into an atmospheric chamber and a partial vacuum chamber;

linkage means connected to the diaphragm means and a butterfly valve located adjacent the first passageway for controlling the communication of partial vacuum to the power chamber as a function of the created pressure differential between the atmospheric and partial vacuum chambers; and

fourth resilient means located in the partial vacuum chamber for placing a predetermined bias on said diaphragm means to delay the created pressure differential operation of the linkage means. 

1. An intensifier for maintaining an operational partial vacuum level of a vacuum powered device within a predetermined range, said intensifier comprising: a housing having a power chamber and an evacuation chamber; first wall means dividing the power chamber into a first chamber and a second chamber; second wall means dividing the evacuation chamber into a third chamber and a fourth chamber; said second wall means having a smaller area than the first wall means; shaft means for rigidly connecting said first wall means to said second wall means; a source of partial vacuum connected to said vacuum powered device; actuating means responsive to movement of said shaft means for alternately porting air at atmospheric pressure and partial vacuum from said source to the first and second chambers of the power chamber to create an operational pressure differential across said first wall means causing said shaft means to reciprocate and correspond-ingly move said second wall means; sensing means connected to the vacuum powered device for comparing the pressure level of the partial vacuum in the vacuum powered device with a control pressure, said sensing means controlling the communication of said partial vacuum to the power chamber for creating the operational pressure differential; first control means connected to the third chamber of the evacuation chamber, the source of partial vacuum, and the vacuum powered device; and second control means connected to the fourth chamber of the evacuation chamber, the source of partial vacuum, and the vacuum powered device, said first and second control means operating in response to movement of said second wall means to alternately inhale and exhale air in the third and fourth chambers from the vacuum powered device to uniformly reduce the pressure level in said vacuum powered device below the available partial vacuum from said source, said reduced level in said vacuum powered device being a function of the areas of said first and second wall means.
 2. The intensifier, as recited in claim 1, wherein said housing includes: a partition wall separating said power chamber from an atmospheric chamber, said partition wall having a first bore, a second bore and a third bore, said partition wall having a first passageway connecting the first and third bores with the source of partial vacuum communicating through said sensing means; said partition wall having a second passageway connecting said first and second bores, said first bore being opened to said atmospheric chamber, said second and third bores being opened to the second chamber and the atmospheric chamber, said shaft being sealed in said second bore and having an internal passage for connectiNg said second bore with said first chamber; first valve means located in said first bore and connected to said shaft means for alternately porting partial vacuum from said first passageway and air at atmospheric pressure from said atmospheric chamber to said second passageway for transmission to said first chamber; and second valve means located in said third bore and connected to said shaft means for alternately porting partial vacuum from said passageway and air at atmospheric pressure from said atmospheric chamber to said second chamber in an opposing sequence to said first valve means to create the operational pressure across the first wall means.
 3. The intensifier, as recited in claim 2, wherein said sensing means permits communication of partial vacuum to said first passageway when the sensed pressure level is above a predetermined value and prevents communication of said partial vacuum to the first passageway when the pressure level equals a predetermined value.
 4. The intensifier, as recited in claim 3, wherein said housing further includes: a projection adjacent said evacuation chamber having a fourth bore and a fifth bore, said housing forming a first annular seat at the bottom of the fourth bore around a first passage to the third chamber, said housing forming a second annular seat at the bottom of the fifth bore around a second passage to the fourth chamber, said housing having a third passageway connecting the fourth and fifth bores with the first passageway, said fourth bore being connected to said source of partial vacuum, said fifth bore being connected to said vacuum powered device and a fourth passageway connecting the fourth bore with the fifth bore to permit the vacuum powered device to be evacuated by the partial vacuum available from said source.
 5. The intensifier, as recited in claim 4,wherein said first control means includes: first flexible tubular means having one end secured to the interior of said fourth bore and an inwardly projecting annular lip on the other end; first resilient means for urging said annular lip of the first flexible tubular means against the first annular seat to close the communication between the first passage going to the third chamber and the third passageway; and first cap means resiliently held against said annular lip of the first flexible tubular means for closing communication between the third chamber and the fourth bore.
 6. The intensifier, as recited in claim 5, wherein said second control means includes: second flexible tubular means having one end secured to the interior of said fifth bore and inwardly projecting annular lip on the other end; second resilient means for urging said annular lip of the second flexible tubular means against the second annular seat to close the communication between the second passage going to the fourth chamber and the third passageway; and second cap means resiliently held against said annular lip of the second flexible tubular means for closing communication between the fourth chamber and the fifth bore.
 7. The intensifier, as recited in claim 6, wherein said first valve means includes: third flexible tubular means having one end secured to the interior of said first bore and an inwardly projecting annular lip on the other end; first stem means located inside said third flexible tubular means; disc means secured to one end of said first stem means; and first spring means located between the annular lip of the third flexible tubular member and a retainer member on the first stem means for urging said first disc means against said annular lip of the third flexible means for closing communication between the first bore and the atmospheric chamber.
 8. The intensifier as recited in claim 7, wherein said second valve means includes: fourth flexible tubular means having one end secured to the interior of the second bore and an inwardly projecting annular lip on the other end; second stem means located Inside said fourth flexible tubular means; second disc means secured to one end of said second stem means; and second spring means located between the annular lip of the fourth flexible tubular means and a retainer on the second stem means for urging said second disc means against said annular lip of the fourth flexible means for closing communication between the third bore and the atmospheric chamber.
 9. The intensifier as recited in claim 8, wherein said intensifier further includes: flow control means located between the connection of the fourth bore and the source of partial vacuum to only permit flow of air from the vacuum powered device toward the source of partial vacuum.
 10. The intensifier, as recited in claim 9, wherein said actuator means further includes: a lever arm pivotally attached to the housing at its midpoint having one end attached to the other end of said first stem means and the other end of said second stem means; and third resilient means secured to said shaft means and said lever arm for alternately holding said first and second disc means against the annular lip of the third and fourth flexible tubular means to permit the partial vacuum and air at atmospheric pressure access to the first and second chambers.
 11. The intensifier, as recited in claim 10, wherein movement of said second wall means in a first mode causes inhalation of air into the third chamber from said fourth passageway connected to the vacuum powered device by unseating said first cap means and exhalation of air from the fourth chamber by overcoming the second resilient means to compress the second flexible tubular means to allow air to pass around the second annular seat and be dumped into the third passageway.
 12. The intensifier, as recited in claim 11, wherein movement of said second wall means in a second mode causes inhalation of air into the fourth chamber from the fifth bore connected to the vacuum powered device by unseating said second cap means and exhalation of air from the third chamber by overcoming the first resilient means to compress the first flexible tubular means to allow air to pass around the second annular seat and be dumped into the third passageway.
 13. The intensifier, as recited in claim 12, wherein said sensing means includes: a housing having an interior cavity with an atmospheric port and an operational partial vacuum port connected to the vacuum powered device; diaphragm means for dividing the internal cavity into an atmospheric chamber and a partial vacuum chamber; linkage means connected to the diaphragm means and a butterfly valve located adjacent the first passageway for controlling the communication of partial vacuum to the power chamber as a function of the created pressure differential between the atmospheric and partial vacuum chambers; and fourth resilient means located in the partial vacuum chamber for placing a predetermined bias on said diaphragm means to delay the created pressure differential operation of the linkage means. 